We're going to go to president obama's high-stakes showdown over syria. A flurry of activity as israel had a missile test in the mediterranean. This as the president tries to get members of congress to authorize military action. And president bashar al assad is taunting president obama. Martha raddatz has the latest. Martha? Reporter: This is the biggest test of president obama's presidency. And the administration is working nonstop to gain support from congress and the american people. The president reached across the aisle to make his case, meeting with two of his harshest critics, in an effort to gain momentum for congressional approval to use military force against syria. I think we found some areas where we can work together. But we have a long way to go. We urged the president to up his game. And inform the american people, what does it mean when and the opposition moves. Reporter: Senator mccain has criticized the president for not taking enough action in syria, he is urging his colleagues to support the resolution. A vote against the resolution by congress I think would be catastrophic. It would undermine the credibility of the united states of america and the president. Reporter: Meanwhile, president bashar al assad, looking poised and immaculately dressed, came out in defiance. Telling the french newspaper, "la figaro" saying there's no proof that chemical weapons were used. And he said the middle east is a powder keg. And the fire is getting closer, he said. No one knows what will happen. Everyone will lose control once the keg blows up. Chaos and extremism will spread. The risk of a regional war exists. Today, top congressional leaders will be summoned to the white house, george. This is a full-court press. No question about that. What about the alarms that went up when russia reported a missile launch over the seas near syria? Reporter: Russia first to report it. And then, the israeli ministry of defense confirming there was a long-range missile test this morning. They do these kinds of tests occasionally. But this is a very sensitive time to be testing a missile and only adds to the tension in the region. It does.

This transcript has been automatically generated and may not be 100% accurate.

Obama Puts Off Military Action in Syria

The president's decision has sparked heated debate around the globe.

White House Pushes for Congressional Approval for Syria Strike

Obama administration making an all-out effort to convince congress of need for military intervention

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